Don't think my first post took so here goes again. I have opted for the 0320 Lycoming and would like some input on weather to go fuel injection or carb. don't really know the advantages but have been flying carb for 20 trouble free years. It is difficult to make an informed decision. Any input would be greatly appreciated. Thanks.
Van's Air Force
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Fuel Inject or not to
- Thread starter rcarson
- Start date
strahler13
Well Known Member
Carb
I vote for carbs. I've seen too many FI owners crank, and crank, and crank prior to starting. Mine always starts on the 2nd blade.
Mark
I vote for carbs. I've seen too many FI owners crank, and crank, and crank prior to starting. Mine always starts on the 2nd blade.
Mark
When I was flight instructing years ago, we had a fleet of brand new C-172's, all FI. I had the starting sequence down to a science, and even hot I could get it to fire by the 2nd or 3rd blade. But yeah, on a hot day a hot start can be a bitch.
Carb is cheaper initially, and probably easier to install and maintain. However the long term bennies of FI are, as was mentioned, that you can run LOP with a good EI and better control of CHT and internal pressures on the engine, and longer life. There are some good articles on Avweb for both, but personally I'd like to go FI when it comes time for the motor.
Carb is cheaper initially, and probably easier to install and maintain. However the long term bennies of FI are, as was mentioned, that you can run LOP with a good EI and better control of CHT and internal pressures on the engine, and longer life. There are some good articles on Avweb for both, but personally I'd like to go FI when it comes time for the motor.
Garage Guy
Well Known Member
Flying inverted.
Though if you don't also have an inverted oil system, having the engine quit when you go inverted and lose oil pressure is probably what you want to happen.
As an anecdotal data point: in my experience, people who deal with aircraft engines a lot more than I do, like A&P's, tend to prefer carburetors. I was a bit surprised by that the first couple of times I asked the question, but the trend has held up. Reasons given are simplicity, reliability, repairability.
We have LASAR ignition with our O-360-A1A, and cruising at altitude I can lean about as well as folks flying injected engines say they can. Carburetor ice has been a total non-issue (so far).
That said, if I was building, I'd probably go with injection and some kind of inverted oil system, to open up the aerobatic envelope a bit. But the carbed engine we have has been working out quite well.
--Paul
Jerry Cochran
Well Known Member
I struggled with the same issue but finally bit hard, spent the extra $$$ and never looked back. Hard starting? Pretty much a myth, just have to learn the drill. I'll admit not as easy as carb tho... I just love running LOP, but of course it takes sensors to do so... Above 8000' I'll get 25+mpg (statute) saving money and extending range.
YMMV of course...
This is really a personally decision.
Personally I prefer carbs. Been flying behind them for over 43 years. they are simple, cheap, run on less than 3 lbs. of fuel pressure, and rarely have problems.
When I built my -6, I looked into FI but decided that it would never be worth the several thousand extra dollars.
Personally I prefer carbs. Been flying behind them for over 43 years. they are simple, cheap, run on less than 3 lbs. of fuel pressure, and rarely have problems.
When I built my -6, I looked into FI but decided that it would never be worth the several thousand extra dollars.
Finley Atherton
Well Known Member
I have an 0-320 (carb) and if I could choose again I would still go carb. Less weight, a bit cheaper, simple, easy to install, maintain and adjust and easy starting.
You may not be able to run LOP on all 4 cylinders with a carb (although some will) but you should get similar fuel economy if you lean it as much as possible (just in from the point of roughness). At this setting the EGTs should be around peak and this will give similar fuel economy to LOP. All the experts and engine manufactures say operating at peak (or any mixture setting) is no problem and will not damage the engine provided you are under about 65% power (Lycoming has the limit at 75% power).
Fin
9A
You may not be able to run LOP on all 4 cylinders with a carb (although some will) but you should get similar fuel economy if you lean it as much as possible (just in from the point of roughness). At this setting the EGTs should be around peak and this will give similar fuel economy to LOP. All the experts and engine manufactures say operating at peak (or any mixture setting) is no problem and will not damage the engine provided you are under about 65% power (Lycoming has the limit at 75% power).
Fin
9A
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With FI you won't have the 1.1"-1.5" pressure drop that the carb needs to operate so you'll pick up about 5% more power, so your 160 hp will go up to about 168 hp. I like a carb for its simplicity, but I have no druthers. I think the new electronic FIs, such as Ross sells, are better than the mechanical ones. If you mount the automotive injectors in the induction tubes on the bottom of the engine, you will have no problem with heat soaking as you do with a distributor on top of the engine.
Finley Atherton
Well Known Member
I certainly seems logical that the injected engine would have more power at full throttle but why isn't this shown in any of Lycomings tables, charts or specifications which shown both the carb and injected engines at 160 hp?
Fin
9A
rv9aviator
Well Known Member
I'm going with a carb for simplicity reasons. I want the first flights to be as generic as possible. Later I may switch to FI and electronic ignition but my engine was a running engine off a Cherokee 140 with less than 300 hours on a factory reman. This way I have a known entity and am pretty sure I won't have any fuel or ignition surprises on the first flight. At least that is what I'm hoping for.
ratc
Well Known Member
FI, Carb OR TBI?
Just an addition to the mix, have you considered a Throttle Body Injector?
On the positive side:-
More even fuel distribution than a carb, although not as good as FI.
OK for inverted flight since there is no float chamber.
Auto fuel can also be used.
On the negative side:-
Very few units in use so useful data is scarce.
Unorthodox starting and shutdown procedures.
A very simple system which has been beautifully engineered by Rotec.
Check out their web site. http://www.rotectbi.com/
Just an addition to the mix, have you considered a Throttle Body Injector?
On the positive side:-
More even fuel distribution than a carb, although not as good as FI.
OK for inverted flight since there is no float chamber.
Auto fuel can also be used.
On the negative side:-
Very few units in use so useful data is scarce.
Unorthodox starting and shutdown procedures.
A very simple system which has been beautifully engineered by Rotec.
Check out their web site. http://www.rotectbi.com/
I have been very happy with the Carb's on both our RV-8 and RV-6...and all the airplanes I have had before. Simple, easy to fix with minimal parts if required....and very few problems with hot starts. Mine even runs very nicely with all four cylinders LOP!
So why are going with Injection on the new RV-3? mostly to try something different, and because I want the airplane to be capable of more inverted aerobatics. The existing planes are great for most all of the gentleman's "Acro" that I do daily. I'd like to push the -3 a little more. And frankly, I want to experiment with different things, so we'll give the injection a try.
Both work - for utter simplicity, I've always had good luck with carbs.
Paul
So why are going with Injection on the new RV-3? mostly to try something different, and because I want the airplane to be capable of more inverted aerobatics. The existing planes are great for most all of the gentleman's "Acro" that I do daily. I'd like to push the -3 a little more. And frankly, I want to experiment with different things, so we'll give the injection a try.
Both work - for utter simplicity, I've always had good luck with carbs.
Paul
erich weaver
Well Known Member
Never quite understood the simplicity argument. HOw is an AFP fuel injection system complicated? And I for one have never had any starting issues. Maintenance? Geez, I think I blew out the injectors once.
Erich
Mark Albery
Well Known Member
I've had both flavours of RV-4 and prefer the injected. A couple of points not mentioned is the relative immunity to carb ice and the option to use a cold air induction system for a bit more power with injected.
Admittedly, I've not experienced carb ice in my present mount, but that's mostly flying around Southern California. It was a different matter in my previous home and the accompanying British weather
Admittedly, I've not experienced carb ice in my present mount, but that's mostly flying around Southern California. It was a different matter in my previous home and the accompanying British weather
That's a good question Fin. One of the things that Klaus noticed with the FI I designed for him is that he got more power. You have to figure that if your MAP goes from 28.4" at sea-level with an MA4 to 29.9" with just a throttle valve and no drop you're going to see a little more power.
CArb Ice
One thing I noticed reading the UK accident reports was the high percentage of reports indicating carb icing may have been a factor in the accident. Here with a humid climate I'd opt for FI every time for that fact alone.
Once you find what works for your engine starting hot or cold is not a problem. In fact cold starts at this time of the year are better with FI.
Peter
One thing I noticed reading the UK accident reports was the high percentage of reports indicating carb icing may have been a factor in the accident. Here with a humid climate I'd opt for FI every time for that fact alone.
Once you find what works for your engine starting hot or cold is not a problem. In fact cold starts at this time of the year are better with FI.
Peter
Andy Hill
Well Known Member
Aerobatics v FI/Carb...
Ability to do aerobatics is, IMHO, one of the big plus factors of Carb v FI (leaving aside the TBI option). It is not necessary to go down the route of Inverted Oil/Fuel as well, unless you really want to do (extended) inverted flight.
The downside of a carb shows up when you try a stall turn (Hammerhead), since the Carb tends to cut off at about +0.2g - so the Vertical Upline will see the engine falter, even stop. No issue, conduct the Stall Turn (a little harder without the prop wash), hold the downline, then pull and the increasing airspeed and 'g' tend to rotate the prop and restart the engine... but not ideal, and some owners I find tend to get a little concerned
Even a loop, flown in a display/competition type manner e.g. floating over the top, will see the engine falter.
Clearly limiting Aeros to +ve 'g' throughout gets round this, but you did ask for opinions...
Andy
RV-8 G-HILZ
RV-8tors
Ability to do aerobatics is, IMHO, one of the big plus factors of Carb v FI (leaving aside the TBI option). It is not necessary to go down the route of Inverted Oil/Fuel as well, unless you really want to do (extended) inverted flight.
The downside of a carb shows up when you try a stall turn (Hammerhead), since the Carb tends to cut off at about +0.2g - so the Vertical Upline will see the engine falter, even stop. No issue, conduct the Stall Turn (a little harder without the prop wash), hold the downline, then pull and the increasing airspeed and 'g' tend to rotate the prop and restart the engine... but not ideal, and some owners I find tend to get a little concerned
Even a loop, flown in a display/competition type manner e.g. floating over the top, will see the engine falter.Clearly limiting Aeros to +ve 'g' throughout gets round this, but you did ask for opinions...
Andy
RV-8 G-HILZ
RV-8tors
carguy614
Well Known Member
I vote for FI
Today, I mean TODAY...When you look at the real price difference of AFP fuel injection and a carb installation, you will see that the gap has narrowed quite a bit. A NEW carb is nearly 2 grand now!! Yikes..Yes, there is the fuel pump that fits in the mix, as well as a couple of extra hoses, and a bit more work for installation in the RV, but that price delta has indeed shrunk a lot these last couple of years. Fuel is also more expensive, and I suspect will rise in price even further. That makes the meager fuel savings that the FI system can offer an issue worth considering. Not to mention the SNORKLE!!!!Using AFP will allow you to eliminate the intake bulge from the cowl, (10 Knots?) and draw air from the lower cooling ramp. LOP operation is now possible, Maintenance is in reality, no issue, a touch more horsepower, and no carb ice. The downside is learning the hot start trick.
Absolutely nothing wrong with a carb or Ellison installation, but I tell you, I've built my last carbureted airplane.....
Regards,
Chris
Today, I mean TODAY...When you look at the real price difference of AFP fuel injection and a carb installation, you will see that the gap has narrowed quite a bit. A NEW carb is nearly 2 grand now!! Yikes..Yes, there is the fuel pump that fits in the mix, as well as a couple of extra hoses, and a bit more work for installation in the RV, but that price delta has indeed shrunk a lot these last couple of years. Fuel is also more expensive, and I suspect will rise in price even further. That makes the meager fuel savings that the FI system can offer an issue worth considering. Not to mention the SNORKLE!!!!Using AFP will allow you to eliminate the intake bulge from the cowl, (10 Knots?) and draw air from the lower cooling ramp. LOP operation is now possible, Maintenance is in reality, no issue, a touch more horsepower, and no carb ice. The downside is learning the hot start trick.
Absolutely nothing wrong with a carb or Ellison installation, but I tell you, I've built my last carbureted airplane.....
Regards,
Chris
Walt
Well Known Member
The "Snorkel" is really about looks, there is no speed/aerodynamic drag difference or speed advantage between the smooth cowl and the snorkel cowl. The smooth IO360 cowl is wider than the O360 snorkel cowl which probably accounts for the equal performance.
db1yg
Well Known Member
I flew a Cherokee 180/carb for 5 years---easy to maintain, easy starting, very basic/reliable/simple system. Never had to touch the carb. Did have a couple of incidences of carb ice.
I flew a Mooney 201 (M20J) Lyc 200hp/Bendix FI for 12 years---good efficiency, smooth running, a little challenging to hot start (until I got a SkyTec starter), but expensive to maintain ($1200 to rebuild the servo).
My RV9a has an Eci 0360/carb with a LS PIII EI. I did this for simplicity/easy starting/and low maintenance cost. HOWEVER, I have just taken delivery of an AFP FI system that I will be installing when the weather warms a little here in Prescott. Why?? Although I could run my carb LOP, it was not as efficient as I wanted, #s 3 and 4 were just barely LOP while 1 and 2 were deep LOP and the cht spread, due to the uneven power output, was wider than I like. I am hoping for an even smoother engine and slightly better efficiency.
BTW, if anyone wants to buy a MA4-5 carb (brass floats), a mechanical fuel pump, and a boost pump for a 360 carb engine let me know---300 hrs on all.
Cheers,
db
I flew a Mooney 201 (M20J) Lyc 200hp/Bendix FI for 12 years---good efficiency, smooth running, a little challenging to hot start (until I got a SkyTec starter), but expensive to maintain ($1200 to rebuild the servo).
My RV9a has an Eci 0360/carb with a LS PIII EI. I did this for simplicity/easy starting/and low maintenance cost. HOWEVER, I have just taken delivery of an AFP FI system that I will be installing when the weather warms a little here in Prescott. Why?? Although I could run my carb LOP, it was not as efficient as I wanted, #s 3 and 4 were just barely LOP while 1 and 2 were deep LOP and the cht spread, due to the uneven power output, was wider than I like. I am hoping for an even smoother engine and slightly better efficiency.
BTW, if anyone wants to buy a MA4-5 carb (brass floats), a mechanical fuel pump, and a boost pump for a 360 carb engine let me know---300 hrs on all.
Cheers,
db
Correct me if I'm wrong, but doing a non-scientific study of engine prices on Van's website, FI over a similar carb set up is only two grand more. Seems like over the life of the engine you could easily recoup that cost in fuel savings alone with LOP operations, not to mention the added benefits. Thoughts?
calake
Member
Funny thing about this question; ask a carb guy and he say carb. Ask a FI guy and he says FI. I had the same issue a year ago and instead of asking people with airplanes, I asked the guys who build the engines. I ended up with FI and I do love it so far. I did have to learn the "hot start" procedure, but it is easy now.
C A Mansfield
N33WE flying for two weeks with IO-360
C A Mansfield
N33WE flying for two weeks with IO-360
Why is that funny? Obviously a guy that has a carb will say go carb. If he liked FI he would have FI.
I guess I'm not getting the LOP operation with a carb. On my friend's O-320, as long as the throttle was wide open, the EGT of all of the cylinders was very close. However, at part throttle, with the throttle plate angled forward, the two front cylinders ran richer than the two rear cylinders, since the throttle plate seemed to shoot more fuel droplets forward.
One thing I did notice about the riser above the carb in the pan is that it didn't have a smooth transition from the riser to the four openings for the cylinders, which could cause turbulence. On my carb installation I used JB Weld to form a smooth transition from the air box into the carb throat, with nice rounded edges to promote Coanda effect to help guide the air into the carb throat. I've also inserted a thin aluminum air guide made of crossed plates to form an X that goes from the throat to the venturi to help straighten the flow. I went to a lot of trouble to insure that the air entering the carb did so smoothly. Since I get total pressure recovery, it must be working well
Could it be that your inability to lean evenly might not be a result of the carb but from having turbulent air entering the carb throat due to iregularities in the filter air box or a step from the plate that attaches to the carb throat?
It is essential that you take as much care with the air path from the filter box to the carb as you would in sealing control gaps and other aerodynamic niceties. Often people get the idea that because the engine is "sucking-in" air that it will flow correctly. Any time you trip air over a sharp edge you will get turbulence.
One thing I did notice about the riser above the carb in the pan is that it didn't have a smooth transition from the riser to the four openings for the cylinders, which could cause turbulence. On my carb installation I used JB Weld to form a smooth transition from the air box into the carb throat, with nice rounded edges to promote Coanda effect to help guide the air into the carb throat. I've also inserted a thin aluminum air guide made of crossed plates to form an X that goes from the throat to the venturi to help straighten the flow. I went to a lot of trouble to insure that the air entering the carb did so smoothly. Since I get total pressure recovery, it must be working well
Could it be that your inability to lean evenly might not be a result of the carb but from having turbulent air entering the carb throat due to iregularities in the filter air box or a step from the plate that attaches to the carb throat?
It is essential that you take as much care with the air path from the filter box to the carb as you would in sealing control gaps and other aerodynamic niceties. Often people get the idea that because the engine is "sucking-in" air that it will flow correctly. Any time you trip air over a sharp edge you will get turbulence.
Greg Arehart
Well Known Member
My opinion: I like my FI setup. Price differential was insignificant when I bought in 2007. I like the no carb ice feature, and can lean effectively at high altitude (I can be burning 6-6.5 gph at 175 mph at 17,500 ft). I've had zero issues with hot starts - I think the newer engines are easier to hot start than the older ones. But, I don't have anything against carbs.
my two cents.
greg
my two cents.
greg
To Fi or Not to Fi
Thanks for all of the great input however It has made one thing very clear. Both are reliable proven intakes that have both advantages and disadvantages. I suppose it depends on which you prefer to live with. Glad to know there is a medium like this to get hands on info from.
Thanks for all of the great input however It has made one thing very clear. Both are reliable proven intakes that have both advantages and disadvantages. I suppose it depends on which you prefer to live with. Glad to know there is a medium like this to get hands on info from.
Mike S
Senior Curmudgeon
Not just induction..........
You know, the same basic statement can be made about a lot of the sectors of this hobby/obsession------EFIS comes to mind. Tool vendors, interiors-----big list.
And, which RV design
You know, the same basic statement can be made about a lot of the sectors of this hobby/obsession------EFIS comes to mind. Tool vendors, interiors-----big list.
And, which RV design
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Jerry Carter
Well Known Member
Save thousands on fuel with F.I.
In the first year, I flew 200 hours in my fuel-injected 7. I run lean-of-peak, using 7.1 gallons per hour at 9,000 ft. Compare this with my previous RV-8A with carb which gobbled up closer to 10 gallons per hour. At a conservative $4 per gallon, I used about 1400 gallons vs 2000 gallons, saving me $2,400 in fuel costs in one year.
You cannot run lean-of-peak with a carb. You're wasting your money with all the fancy gauges showing individual EGT's and CHT's if you can't do any thing to adjust the fuel flow to individual cylinders.
In the first year, I flew 200 hours in my fuel-injected 7. I run lean-of-peak, using 7.1 gallons per hour at 9,000 ft. Compare this with my previous RV-8A with carb which gobbled up closer to 10 gallons per hour. At a conservative $4 per gallon, I used about 1400 gallons vs 2000 gallons, saving me $2,400 in fuel costs in one year.
You cannot run lean-of-peak with a carb. You're wasting your money with all the fancy gauges showing individual EGT's and CHT's if you can't do any thing to adjust the fuel flow to individual cylinders.
Finley Atherton
Well Known Member
I have to respectfully disagree that in cruise, a carb will use substantially more fuel than an injected engine. I am guessing that either your 8A cruised at a higher HP or a higher RPM or that you may not have been aggressively leaning your 8A carb engine (allowable under 60/65% power).
My understanding is that below 60/65%power a carb Lycoming can be aggressively leaned out to the point just before the engine runs rough. At this point most cylinders will likely be close to peak- some could be LOP, some just ROP or possibly all LOP. Lycomings Specific Fuel Consumption graph is virtually flat from around peak to about 50 degrees LOP so there is no significant improvement in fuel economy between running LOP compared to Peak.
This is not just theory. I stand to be corrected, but I am yet to read of an injected I0-320 9A that has better fuel economy than my carb 0-320 9A. In fact the only 9A I know of with possibly sightly better fuel consumption figures is one with an 0-320 (carb)
Fin
9A
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petehowell
Well Known Member
Hi Jerry
Fin and I trade numbers on our 9As with carbs. Running LOP requires a little fiddling, but it is possible and very real. Fin gets a bit better numbers with higher compression. Here are my cruise numbers after 750 hours. ECI kit O-320/Hartzell/E-Mag/P-Mag.
This test just after my Year 4 annual:
8000 ft, -8C, 22.2" MP, 2270 RPM, LOP 6.0-6.1 GPH, carb heat about 1/4 on.
Here is data puked out of the Dynon EMS on a different run showing CHT and EGT peaks:
The carb heat is the trick - we think it adds some turbulence and heat to allow better atomization of the fuel drops and provides better distribution.
It works well for me and Fin!
Fin and I trade numbers on our 9As with carbs. Running LOP requires a little fiddling, but it is possible and very real. Fin gets a bit better numbers with higher compression. Here are my cruise numbers after 750 hours. ECI kit O-320/Hartzell/E-Mag/P-Mag.
This test just after my Year 4 annual:
8000 ft, -8C, 22.2" MP, 2270 RPM, LOP 6.0-6.1 GPH, carb heat about 1/4 on.
Here is data puked out of the Dynon EMS on a different run showing CHT and EGT peaks:
The carb heat is the trick - we think it adds some turbulence and heat to allow better atomization of the fuel drops and provides better distribution.
It works well for me and Fin!
AlexPeterson
Well Known Member
Another consideration - CHT distribution
The ability to have uniform cylinder head temperatures is a plus for FI. Uniformity of temperatures by itself is not that important, but many carb'd planes must run excessively rich to keep the hottest cylinder under control. Of course, many carb'd planes have no issues, but my experience in looking at data from a number of carb'd RV's is that the "cooling" issues with individual cylinders are really mixture distribution problems. I.e., one cylinder is running in the worst place for high cht's, something in the 50 ROP range, while the others are in the LOP areas, running much cooler (like 70 degrees F or more). This also implies that each cylinder is not putting out the same hp, which can make for a less smoothly running engine. Many of us have played around with various baffle modifications trying to cool down the hottest cylinders, only to learn that mixture was the real root cause.
The ability to have uniform cylinder head temperatures is a plus for FI. Uniformity of temperatures by itself is not that important, but many carb'd planes must run excessively rich to keep the hottest cylinder under control. Of course, many carb'd planes have no issues, but my experience in looking at data from a number of carb'd RV's is that the "cooling" issues with individual cylinders are really mixture distribution problems. I.e., one cylinder is running in the worst place for high cht's, something in the 50 ROP range, while the others are in the LOP areas, running much cooler (like 70 degrees F or more). This also implies that each cylinder is not putting out the same hp, which can make for a less smoothly running engine. Many of us have played around with various baffle modifications trying to cool down the hottest cylinders, only to learn that mixture was the real root cause.
Jerry Carter
Well Known Member
I am guessing that either your 8A cruised at a higher HP or a higher RPM or that you may not have been aggressively leaning your 8A carb engine (allowable under 60/65% power). Fin 9A[/QUOTE said:
Finley Atherton
Well Known Member
I think you have hit the nail on the head. Although I was defending the fuel consumption of a carb in my post #34, I accept that it should be easier to get a balanced injected engine to run LOP/economically than a carb.
My carb engine will run at least around peak or leaner but I suppose that some carb engines may have to run richer for smooth operation and economy will suffer.
Also I lean pretty aggressively and although I think the engine is still smooth I am sure some others would feel the engine is a bit rough and would be more comfortable with a richer/less economical mixture. Presumably with a balanced injected engine a pilot should be able to run leaner before their particular definition of roughness is reached than with a carb.
Fin
9A
Fin
9A
N941WR
Legacy Member
Talk to a bush pilot. Based on what I have been told by a number of them, they only want a carb. When asked why, they mention reliability and the ability to repair them in the bush, if needed.
Now, very few of us RV drivers go into the bush (there are exceptions), so this may not be an issue.
Now, very few of us RV drivers go into the bush (there are exceptions), so this may not be an issue.
An engine with EFI will not necessarily get better mixture distribution. If that were the case then the guys who put out injector nozzles matched to individual cylinders would not be in business. I know because in the EFI I designed I have a control to match pairs of cylinders +/-5%.
Not every induction manifold and cylinder breathes exactly the same. A lot of the Reno guys clock their plugs with their ground electrodes pointing at the same direction in the cylinder; do you? C.F. Taylor shows that placing a small dam on either side of the intake valve to direct intake swirl will make that cylinder perform better. Based on this, are all of your valve seats in the heads matched for depth and symmetry of depth so that each cylinder will swirl, or not, equally? There are so many little irregularities that can cause power variations from one cylinder to the next.
BTW, Pete. How about describing what you and Fin have found from the use of carb heat to manage power and smoothness other than just for carb ice protection.
Not every induction manifold and cylinder breathes exactly the same. A lot of the Reno guys clock their plugs with their ground electrodes pointing at the same direction in the cylinder; do you? C.F. Taylor shows that placing a small dam on either side of the intake valve to direct intake swirl will make that cylinder perform better. Based on this, are all of your valve seats in the heads matched for depth and symmetry of depth so that each cylinder will swirl, or not, equally? There are so many little irregularities that can cause power variations from one cylinder to the next.
BTW, Pete. How about describing what you and Fin have found from the use of carb heat to manage power and smoothness other than just for carb ice protection.
That's why, if all other elements of the equation are equal (which they are almost always not...), I lean towards the Carb. Easily fixable in the field with primative tools. Maybe I just need to take some FI systems apart and learn more about how to fix them....
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AlexPeterson
Well Known Member
Yes, that is the whole point - with FI the mixture can be adjusted by changing nozzles as necessary to compensate for different induction air amounts, etc.
Yes, but unless that is done, the FI cannot be said to give better mixture distribution than a carb. GAMI would not be in business if all FI's mixtures are perfect! I just had the six injectors on my 300ZX changed and when they tested the old ones they were not balanced. My point is that carbs and nozzles and induction systems are all flawed and neither carb nor FI is better than the other. If your induction system does not give the same amount of air to each cylinder and you change the nozzle to to balance EGT or CHT, that cylinder will not produce the same power as the others. If you want good mixture distribution put a carb or throttle-body on each cylinder. I have no pony in the race; to me carbs or FI or EFI are just grand. Each has its good and bad points. Just don't make extreme claims for either!
Jerry Carter
Well Known Member
Yes, but.......
Changing an injector out requires all the skill needed to operate an open-ended wrench - not exactly rocket surgery, since I can easily do it! I was lucky with my engine, a new YIO-360-M1B from Vans, in that the cylinders all leaned at the same fuel flow (0.0 gal per hr difference as shown on the Dynon). But if the cylinders had shown that I needed to adjust the fuel distribution, at least I had the option of changing out the injectors. What do you do to even out the fuel flow with a carb? I realize your comment about putting a carb or throttle body on each cylinder is tongue-in-cheek, but really?
I stick to my claim of fuel savings with fuel injection. I agree with the advantages of simplicity associated with the carb - my lawnmower (when I had one) didn't use fuel injection either!
Changing an injector out requires all the skill needed to operate an open-ended wrench - not exactly rocket surgery, since I can easily do it! I was lucky with my engine, a new YIO-360-M1B from Vans, in that the cylinders all leaned at the same fuel flow (0.0 gal per hr difference as shown on the Dynon). But if the cylinders had shown that I needed to adjust the fuel distribution, at least I had the option of changing out the injectors. What do you do to even out the fuel flow with a carb? I realize your comment about putting a carb or throttle body on each cylinder is tongue-in-cheek, but really?
I stick to my claim of fuel savings with fuel injection. I agree with the advantages of simplicity associated with the carb - my lawnmower (when I had one) didn't use fuel injection either!
AK4x4
Well Known Member
Fuel Injection
I would recomend Fuel Injection. Both systems are easy to work on if you are familiar with them...and both can leave you parked if you are not. That being said where fuel injection shines is fuel atomization. Having fuel pressure to atomize fuel is nice espcially when its cold out or you are operating at part throttle remember vapor burns not liquid...hence the requirment for carb heat to get optimum leaning in a carb you are boiling the liquid into vapor. Carb heat all else being equal costs power. A correctly balanced and setup FI system at lower power settings outperforms a carb. As far as WOT differances it depends. The standard bendix based FI usally installed on Lycoming type engines performs about the same as a carb because it has a restricive venturi just like a carb with the associated 1-1.5" drop in manifold pressure. RV's carb or FI get close to 30" due to ram air effects. The ECI FI system and other throttle body based systems without a venturi will have a power advantage over carb or bendix type FI.
my .02 good luck, Russ
I would recomend Fuel Injection. Both systems are easy to work on if you are familiar with them...and both can leave you parked if you are not. That being said where fuel injection shines is fuel atomization. Having fuel pressure to atomize fuel is nice espcially when its cold out or you are operating at part throttle remember vapor burns not liquid...hence the requirment for carb heat to get optimum leaning in a carb you are boiling the liquid into vapor. Carb heat all else being equal costs power. A correctly balanced and setup FI system at lower power settings outperforms a carb. As far as WOT differances it depends. The standard bendix based FI usally installed on Lycoming type engines performs about the same as a carb because it has a restricive venturi just like a carb with the associated 1-1.5" drop in manifold pressure. RV's carb or FI get close to 30" due to ram air effects. The ECI FI system and other throttle body based systems without a venturi will have a power advantage over carb or bendix type FI.
my .02 good luck, Russ
Not that I've heard
With my limited bush experience there is very little difference in reliability or any preference between FI and carbs. Most bush planes were built well before FI was common though. What really defines a bush plane is how how rugged the airframe is, how fast it can get off the water and how big of a load it can carry. If an engine goes bad, they usually just fly out a new engine or spare cyliders.
One engine to watch though is the R-1340 in the old piston otters. It's geared and loves to blow cylinders. Coincidently, it also has a carb. Not that a RV has to worry about that engine.
With my limited bush experience there is very little difference in reliability or any preference between FI and carbs. Most bush planes were built well before FI was common though. What really defines a bush plane is how how rugged the airframe is, how fast it can get off the water and how big of a load it can carry. If an engine goes bad, they usually just fly out a new engine or spare cyliders.
One engine to watch though is the R-1340 in the old piston otters. It's geared and loves to blow cylinders. Coincidently, it also has a carb. Not that a RV has to worry about that engine.
Garage Guy
Well Known Member
Are there many piston Otters left? Seems like all the commercial operators have converted to PT-6's. Too bad, because there was really nothing like the sound of a piston Otter getting off the water.
To make this RV related, I see that http://www.bush-planes.com/BushPlanePistonEngines.html, which talks about all the great bushplane engines including R-1340's and PT-6's, says of the O-320 and O-360 Lycomings: "These engines are by far the best light plane aero engines ever made." Injected or not
.--Paul
Not too many from what I have seen. There was always one around. Out numbered by the turbine versions, PT-6 or Garrett. Polish Otters are something to see. 1000hp piston engine in an airplane designed for 600hp. It does look quite remarkable. Havn't heard any major problems with it either.
Yes, the radial engines sure do sound nice. Nothing quite like being buzzed by a Beaver. In my books, the Beaver with it's Wasp Jr. is second only to a RV with a Lycoming. [not intending to ridicule the alternative engine guys]
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